Elthon and Casey make two claims. There is no Fo - An anomaly relative to crystal fractionation in gabbro mineral chemistry which would require something as exotic as the Soret effect for its explanation; the Soret effect would not produce the anomalies actually observed in orthopyroxene mineral chemistry and in phase appearance anyway. Their general point that these anomalies (in mineral chemistry and phase appearance) may be due to some process other than the Soret effect has merit, as noted in the original paper. The authors therefore also discuss below some additional features and tests of applicability of a Soret hypothesis to spreading-center gabbros. Finally, they re-emphasize the small magnitude of the Soret effect as it may be manifest in these rocks. This emphasis was overlooked by Elthon and Casey and many other readers